During the Permian (280-235 Ma), the ice age ended and the world warmed
up. There was a rapid evolution of a range of plants including the
Ginkgoales and Bennettites, as well as the dominant flora of the era; the
Glossopterids. For the first time, seed plants became the dominant
reproductive type.

The continental drifting of the Carboniferous era
led to the formation of the super-continent Pangea by the early-Permian (300
Ma).

This led to a relatively cool climate with much glaciation, but
by the mid Permian the climate was warming. As the continental ice sheets
contracted, the waters rose and many parts of Australia and other continents
became flooded with shallow seas.

That said, the climate was still
cool and many areas of high altitude remained covered in snow.
Cool-temperate swamps became a common feature of the landscape (particularly
in Australia) and aside from that produced in the Carboniferous, a lot of
coal was also produced in the Permian.

Some significant groups of
plants evolved during the Permian in the climatic conditions which became
progressively drier; these being the Bennettites, Cycads, Ginkgos and
Glossopterids.

Cycadales: The Cycads

The
cycads first appear in the fossil record dating back to 280 Ma whereafter
their fossils (especially compression fossils) become very common. The early
cycads grew to as much as 15 metres or as little as three metres which is
similar to modern cycads. In fact there is remarkable similarity between
extant cycad species and many of the fossilised specimens which have been
discovered.

The cycads were all dioecious (male and female plants) and had a
distinctive trunk upon which grew 'fronds' composed of pinnate leaves.
The trunk was sometimes branched and is composed of leaf bases. The
female reproductive structures of cycads are called megasporophylls
which are modified leaves and contain the ovules. The male reproductive
structures are also megasporophylls which contain pollen sacks. These
features have been well-preserved in fossils.

The origins of
cycads are not entirely clear, however it is suspected that they evolved
from the Medulosaceae; a family of Seed Ferns.

Bennettitales (Bennettites)

The Bennettites are very
similar to Cycads, and were widely spread across the planet between the
early Triassic to late Cretaceous (248-140 Ma).

It was once
considered that the Bennettales might have been a precursor to flowering
plants, however this now appears not to be the case. This conclusion was
drawn from the Bennettite Williamsoniella coronata and W.
gigas which has reproductive structures which appear to be very
"flower-like" however there are other morphological features which
differentiate them, such as the presence of one instead of two
integuments surrounding the ovule (Willis
& McElwain 2002).

Like Cycads, the Bennettites had long
'frond-like' pinnate leaves which radiated from a central trunk. Unlike
Cycads, it appears that the Bennettites were deciduous.

Ginkgoales (Ginkgos)

The Ginkgoales first appear in the
early Permian fossil record (c.280 Ma) and are limited today to a single
species; Ginkgo biloba which has become popular in recent times
for its herbal qualities. G. biloba is a native of China and
has been cultivated for centuries.

Ginkgo bioloba.

At their peak, the Ginkgoales were represented by
approximately 16 genera which were distributed throughout many parts of
the world. The leaf morphology of the Ginkgoales differed significantly
between species; from almost entire leaves to heavily lobed specimens.
However ginkgoalean leaves are often quite recognisable for their
dichotomous venation and their distinctive shape which resembles the
leaves of the maidenhar fern and is the origin of their common name
"maidenhair tree".

Many fossilised leaves of Ginkgoales have
been found. It is widely thought that the Ginkgoes were deciduous (which
is consistent with high rates of leaf fossilisation) and also because
G. biloba is winter-deciduous. G. biloba is also
dioecious (male and female trees) and so were its ancestors. The male
trees produce catkins which release pollen, and female trees produce
ovules which are arranged on a similar structure. (For more information
on Ginkgoes, refer to the
Ginkgo Page).

The other significant group of plants to develop in the Permian
were the Glossopterids.